A device for producing coreless film rolls is known from WO 99/06312. The device described herein comprises a roll holder which receives a film roll comprising a film sheet to be wound off. This film sheet is an unstretched film sheet. The film sheet is wound off this film roll, stretched with the aid of a plurality of rolls and wound onto a winding mandrel. For the purpose of stretching the film at least one of the deflection rollers is embossed. Further, the rotational velocity of the individual deflection rollers can be varied such that stretching is effected. With the aid of a control device the film sheet is wound up to the winding mandrel in such a manner that the first layers remain unstretched or are wound up at a low tension and only the following layers of the film sheet are prestretched. This allows a coreless film roll to be produced which can be removed from the winding mandrel.
For removing the coreless film roll from the winding mandrel, winding mandrels are known which comprise a plurality of longitudinal segments and/or holding elements which are displaceable in radial direction. Displacement is effected by a pneumatic unit. With the aid of the pneumatic unit it is thus possible to change the circumference of the winding mandrel, i.e. the joint circumference of the segments arranged on a cylinder shell.
The production of coreless film rolls using the device known from WO 90/06312 has the drawback that the winding mandrel, together with the film sheet wound up to the winding mandrel, must be manually taken out of the machine since the prestretched film must calm down before the winding mandrel can be removed. Thus the film must be allowed to settle over a certain period of time prior to removal of the winding mandrel. The manual action required for this purpose increases the production costs in particular for prestretched film rolls.